This invention relates to a unique drive arrangement for electrically driving a vehicle such that the floor profile of the vehicle can be significantly lower along a greater length of the vehicle than was the case in the prior art.
Mass transit vehicles, such as buses or trolley cars, typically have seats aligned at the lateral sides of the vehicle, with a central aisle and floor extending along the vehicle. In order to facilitate entering and exiting from the vehicle, it would be desirable to have the vehicle floor and aisle positioned relatively low to the ground. This would provide increased passenger space within the body of the vehicle, and may allow the overall height of the mass transit vehicle to be reduced. Other advantages to having a lower floor profile include improved handicapped access and greater ease in the loading and unloading of passengers.
Mass transit vehicles typically have several axles which support and drive or steer the vehicle. Recently, applicant has proposed electric motor drives for such vehicles. If the axle is a driving axle, then electric motors can be used to generate torque to drive the wheels. In a typical configuration, a centrally located electric motor drives two opposed wheels at the sides of the vehicle by way of a conventional axle. A driveshaft is used to connect the motor to the axle. The electric motor, driveshaft, and axle are connected to each other in line along a longitudinal axis of the vehicle.
This configuration takes up a significant amount of packaging space and requires the floor profile to be raised to clear the motor, driveshaft and axle. Because these components are aligned along the longitudinal axis of the vehicle, the floor profile must be raised for a significant length of the vehicle. Raising the floor profile in such a manner reduces the amount of available passenger space within the vehicle and requires the passengers to climb up to a platform above the axle.
Thus, it is desirable to have an electric motor mounting configuration that reduces the length over which the floor profile has to be raised. This increases the available passenger space within the vehicle and allows for a greater portion of the vehicle floor to be closer to the ground to improve access to the vehicle.
A vehicle drive unit assembly includes a rear drive axle extending between a pair of vehicle wheels. An input is operably connected to the drive axle to provide torque to the drive axle to drive the vehicle wheels. An electric motor is connected to the input and is mounted above the drive axle. Preferably, the electric motor is mounted directly above the differential in the drive axle.
This mounting configuration improves packaging and increases passenger compartment size by moving the electric motor above the drive axle. This allows the interior vehicle floor to be lowered along a greater length of the vehicle resulting in improved utilization of the passenger compartment.